This is a congenital abnormality characterized by a fleshy, raised, yellow
papillomatous nodule, usually appearing on the head and neck. Aside from cosmetic
issues, there is a definitely increased risk of malignancies, particularly
basal cell carcinomas, arising within these lesions. A complete excision is
usually curative.

Didymosis aplasticosebacea: coexistence of aplasia cutis congenita
and nevus sebaceus may be explained as a twin spot phenomenon.

Happle R, Konig A.

Department of Dermatology, University Hospital Marburg, Germany.

Dermatology 2001;202(3):246-8 Abstract quote

BACKGROUND: Co-occurrence of aplasia cutis congenita and nevus sebaceus
has sometimes been observed.

OBJECTIVE: We propose a genetic mechanism that may explain this coexistence
of two different congenital skin disorders.

Methods and RESULTS: We review 15 cases as reported in the literature
and present an additional case. To explain the temporal and spatial
proximity of the two skin lesions we advance the concept of twin spotting
for which we propose the term didymosis (Greek didymos = twin). In an
embryo heterozygous for two different recessive mutations localized
on either of a pair of homologous chromosomes, an event of somatic recombination
would occur at an early developmental stage, giving rise to two different
cell clones homozygous for either mutation.

CONCLUSION: The concept of didymosis aplasticosebacea is so far hypothetical.
Future molecular research may show whether this concept holds true.

APOCRINE CARCINOMA

Tubular apocrine carcinoma arising in a nevus sebaceus of Jadassohn.

Jacyk WK, Requena L, Sanchez Yus E, Judd MJ.

Department of Dermatology, University of Pretoria, Republic of South
Africa.

Am J Dermatopathol 1998 Aug;20(4):389-92 Abstract quote

We present an example of tubular carcinoma that developed within a
nevus sebaceus of Jadassohn on the scalp of a 53-year-old woman. The
neoplasm showed features of sebaceous and apocrine differentiation.

We review the literature about the malignant neoplasms arising in the
nevus sebaceus of Jadassohn.

DESMOPLASTIC NEUROEPITHELIAL TUMOR

Desmoplastic neuroepithelial tumor of infancy in the nevus sebaceus
syndrome: report of a unique constellation and review of the literature.

Kopniczky Z, Kobor J, Maraz A, Vajtai I.

Department of Neurosurgery, University of Szeged Health Sciences
Center, Hungary.

Pathol Res Pract 2001;197(4):279-84 Abstract quote

The nevus sebaceus syndrome (NSS) is a neurocutaneous disorder characterized
by unilateral hyperplasia of skin appendages and skeletal hemihypertrophy,
hemimegalencephaly, or hemiatrophy along with disabling seizures. Despite
the proneness of the dermal stigmata to eventually undergo neoplastic
transformation, the malformative lesions of the central nervous system
rarely evolve into frank tumors.

We present the case of a 10-year-old girl with left-sided sebaceus
nevi, ipsilateral enlargement of the skull, and a desmoplastic neuroepithelial
tumor (DNET) in the right fronto-parietal area of the brain. The tumor
was removed by surgery. Histologically, it corresponded to a mitotically
active small-cell anaplastic astrocytoma with genuine desmoplasia. Investigative
methods included immunohistochemical positivity for glial fibrillary
acidic protein, lack of expression of neuronal markers, and ultrastructural
documentation of sheaths of basal lamina and collagen around tumor cells.

A survey of the literature of brain tumors associated with NSS revealed
two cases of histologically verified pilocytic astrocytomas, and one
each of a choroid plexus papilloma, a mixed glioma, and a meningioma,
as well as a subependymal giant cell astrocytoma--the latter possibly
in an overlap syndrome of NSS and tuberous sclerosis.

We hypothesize that the tumor described herein, one involving both
atypical differentiation and enhanced growth potential, is paradigmatic
of neuropathological events to be expected in the NSS.

ECCRINE SPIRADENOMA

Spiradenoma arising in a nevus sebaceus of Jadassohn: case report
and literature review.

Nevus sebaceus (NS) of Jadassohn is usually a verrucous plaque on the
scalp or face that arises secondary to disordered development of epithelial,
pilar, sebaceous, and apocrine structures. The emergence of neoplasia
is a late stage in the natural history of NS. Although most neoplastic
proliferations are benign, several malignant tumors have arisen in this
lesion.

We describe the first case of a benign spiradenoma arising in an NS
on the scalp in a 72-year-old Caucasian woman. Reexcision was recommended
to prevent the development of a second neoplastic process and to avoid
the rare occurrence of a malignant transformation of the existing neoplasia.
The patient declined reexcision and remains under observation. The spectrum
of tumors arising in NS are described and are categorized according
to behavior. Syringocystadenoma papilliferum is the most commonly observed
benign growth, whereas basal cell carcinoma is the most frequently seen
malignant process.

The signs of tumor development (benign or malignant) within an NS are
reviewed, and treatment recommendations are provided. The clinical course
of rare and unique aggressive neoplasms originating in NS is summarized.

NEUROFIBROMATOSIS

Segmental neurofibromatosis in association with nevus sebaceus of
Jadassohn.

Lupton JR, Elgart ML, Sulica VI.

The George Washington University Hospital, Washington, DC 20037,
USA.

J Am Acad Dermatol 2000 Nov;43(5 Pt 2):895-7 Abstract quote

We describe an unusual case involving the simultaneous occurrence of
segmental neurofibromatosis (Type V NF) in a patient with a large nevus
sebaceus of Jadassohn in the same physical distribution.

Causative mechanisms of development of these 2 genetic disorders have
not been definitively linked. Factors producing these diseases probably
involve similar tissues at the same point in development because both
have been reported in association with central nervous system anomalies
and have been classified among the neurocutaneous syndromes.

This is a case of a nevus sebaceus occurring in association with and
in the same physical distribution as segmental NF. These disorders most
likely represent a spectrum of disease within the phakomatoses.

OCULAR CHANGES

A new neurocutaneous syndrome: nevus sebaceus syndrome.

Kucukoduk S, Ozsan H, Turanli AY, Dinc H, Selcuk M.

Department of Pediatrics, Ondokuz Mayis University, Samsun, Turkey.

Cutis 1993 Jun;51(6):437-41 Abstract quote

We describe a case of nevus sebaceus syndrome characterized by a linear
sebaceous nevus, extending on the left half of the face from forehead
to lower neck, including the auricle; alopecia on the temporoparietal
region; generalized hypotonia; insufficiency of eyes in following moving
objects and insufficiency in controlling the head; lipodermoid cysts
in the left and right eyes; bilateral conjunctival masses; corneal vascularization
in the right eye; coloboma of the left eyelid and right optic disc.
T

his is a rare case of a sebaceous nevus occurring concomitantly with
optical and central nervous system abnormalities.

SEBACEOUS CARCINOMA

Sebaceous carcinoma, trichoblastoma, and sebaceoma with features
of trichoblastoma in nevus sebaceus.

A 73-year-old woman had a linear yellowish plaque on the upper part
of her right ear since birth.

She presented because of the sudden growth of a nodule within the plaque.
The plaque was waxy and yellowish, arching around the upper part of
the ear. A reddish to yellowish large nodule was seen within the central
part of the arc-shaped plaque; in addition, a small pigmented nodule,
a small skin-colored nodule, and a few pigmented papules were observed
in the anterior half of the arched plaque.

Histopathologic examination revealed the large nodule to be sebaceous
carcinoma, the small pigmented nodule to be trichoblastoma, the small
skin-colored nodule to be sebaceoma with the features of trichoblastoma,
a few pigmented papules to be superficial trichoblastomas due to primitive
follicular induction, and the linear yellowish plaque to be nevus sebaceus.
Although our literature search revealed scanty reports of definite cases
of sebaceous carcinoma in nevus sebaceus, the presented case demonstrated
the occurrence of sebaceous carcinoma in nevus sebaceus.

Malignant neoplasms occurring in nevus sebaceous seem to be extremely
rare, but care should be taken when a large nodule suddenly grows in
a lesion of nevus sebaceus, especially in older adults. The presented
case also suggested a close relation between trichoblastoma and sebaceoma.
The cytokeratin staining pattern could not distinguish between sebaceous
and follicular neoplasms in our case.

We report a case of a congenital nevus sebaceus with numerous brown
macules and papules in the left auricular region.

In the same lesion, pigmented basal cell carcinomas developed later
in life. Additionally, on the left side of the neck, both shoulders
and the left arm, features of nevus spilus with melanocytic and blue
nevi were present.

Such a combination of nevus sebaceus with melanocytic lesions may be
explained by the concept of twin spotting and represent another case
of phacomatosis pigmentokeratotica.

TRICHOBLASTOMA

Trichoblastoma is the most common neoplasm developed in nevus sebaceus
of Jadassohn: a clinicopathologic study of a series of 155 cases.

Nevus sebaceus of Jadassohn is a hamartoma that combines epidermal,
follicular, sebaceous, and apocrine gland abnormalities. Classically,
several types of cutaneous neoplasms have been associated with this
hamartoma, with basal cell carcinoma being the most frequently described
malignancy.

We studied a series of 155 examples of nevus sebaceus of Jadassohn
with clinicopathologic correlation. Several histopathologic changes
related to the age of the patients were found. In our series, we could
not identify any cases of authentic basal cell carcinoma. In contrast,
several examples of primitive follicular induction and of trichoblastomas
were seen. Other cutaneous hamartomas, hyperplasias, and neoplasms found
in our series of nevus sebaceus of Jadassohn included syringocystadenoma
papilliferum, sebomatricoma, apocrine gland cyst, poroma, different
histopathologic variants of warts (classic warts, tricholemmoma, and
desmoplastic tricholemmoma), primitive follicular induction, and ductal
induction. In our series, no examples of malignant neoplasms were identified.

On the basis of these findings, the classically recommended treatment
for this hamartoma, which consists of early excision to prevent the
development of malignancy, seems to be inappropriate.

Clear cell trichoblastoma in association with a nevus sebaceus.

Tronnier M.

Department of Dermatology, Medical University of Lubeck, Lubeck,
Germany.

Am J Dermatopathol 2001 Apr;23(2):143-5 Abstract quote

Nevus sebaceus is a hamartoma that is frequently associated with various
neoplasms. Among the neoplasms observed in sebaceus nevi, trichoblastomas
are the most common.

The present case, to my knowledge, is the first description of a clear
cell variant of trichoblastoma.

PATHOGENESIS

CHARACTERIZATION

ANDROGEN RECEPTORS

The role of androgen receptors in the clinical course of nevus sebaceus
of Jadassohn.

Nevus sebaceus of Jadassohn (NSJ) is a benign, congenital hamartoma
that often presents at birth, appears to regress in childhood, and grows
during puberty, suggesting possible hormonal control.

We studied 18 cases of NSJ from children and adults for immunohistochemical
evidence of androgen receptor expression. The lesions were evaluated
for location and pattern of immunostaining, and these findings were
compared between age groups, sexes, and to androgen receptor expression
in normal skin. Androgen receptor positivity was seen in the sebaceous
glands, in eccrine glands with and without apocrine change, and rarely
in keratinocytes in the sebaceous nevi. There were no significant differences
in staining location or pattern between the age groups or sexes.

Normal skin showed similar staining in the sebaceous glands but did
not show staining of the eccrine glands or keratinocytes. Androgen receptors
are present in all epithelial components of NSJ, but there is no change
in androgen receptor expression during puberty.

Hemispherectomy has been successfully performed in previous patients;
however, it could have led to marked left hemiparesis with significant
functional morbidity in this patient because of ipsilateral reorganization
of the primary motor cortex.

We describe two sibs (a boy and a girl) suffering from linear nevus
sebaceus of Jadassohn. The parents are not affected.

This rare pattern of familial occurrence prompts us to suggest that
these sibs represent a case of paradominant inheritance of a mosaic
disorder.

PROGNOSIS AND TREATMENT

CHARACTERIZATION

PROGNOSTIC FACTORS

MALIGNANCIES

Nevus sebaceus of Jadassohn: the head and neck manifestations.

Hagan WE.

Laryngoscope 1987 Aug;97(8 Pt 1):909-14 Abstract quote

The nevus sebaceus of Jadassohn (SNJ) is a congenitally-occurring,
hamartomatous disorder of the skin and its adnexa of infrequent occurrence.

This presentation of five cases emphasizes the smooth, waxy, yellow-brown
lesion's progression into a thickened sebaceous tumor of premalignant
predilection. The incidence of neoplastic degeneration of these hamartomatous
nevi may be as high as 30% with the capacity of metastasis occasionally
reported. Because of malignancy risks as well as cosmetic considerations,
early surgical removal is recommended. Previously unreported problems
of dysphagia and malnutrition secondary to pulsion diverticulum at the
esophageal inlet and cleft palate, obliterative aural stenosis with
associated conductive hearing loss are documented.

Regardless of SNJ's occurrence as either an isolated lesion or as the
fully developed syndrome, including mental retardation and epilepsy,
this congenital malformation of the skin, its hair, and sebaceous glands
presents rare and histologically intriguing problems for the practitioner.

BACKGROUND: Prophylactic surgical excision of nevus sebaceus (NS) during
childhood is often recommended because various neoplasms can occur on
NS. The proportion of malignant tumors occurring on NS is highly variable
among the published series, and there are controversies on the nature
of these neoplasms because many of the previously described basal cell
carcinomas could actually be trichoblastomas, which are benign follicular
tumors.

OBJECTIVE: We retrospectively analyzed all cases of NS of our collection,
excised during the period from 1932 through 1998, and recorded all associated
epithelial and nonepithelial changes. We especially differentiated basal
cell carcinomas from trichoblastomas by silhouette analysis and examination
of the stroma. These findings were analyzed according to gender, age,
and localization.

METHODS: Microscopic analysis of NS by two examiners was performed
independently of clinical data.

RESULTS: A total of 596 cases were included from 290 females and 306
males, mean age 25.4 years (range, 1 month to 87 years); 232 were excised
in children younger than 16 years. NSs were located on the scalp in
49.8% of cases. Basal cell carcinomas were found in 5 cases (0.8%, mean
age 39.3 years) and benign tumors in 81 cases (13.6%, mean age 46.3
years). Syringocystadenoma papilliferum (n = 30, 15 males, 15 females)
and trichoblastoma (n = 28, 7 males, 21 females) were the most frequent
benign tumors. NS with associated tumors were located on the scalp in
79% of cases. Only 4 benign tumors (1.7%) and 2 warts were observed
in patients younger than 16 years. Various types of epithelial hyperplasia
were noted that could not be considered neoplasms, as well as epidermal
and apocrine cysts.

CONCLUSION: The rate of malignant tumors arising on NS was very low
and we did not observe such cases in children, who had associated benign
tumors in only 1.7% of cases. Benign neoplasms were common and most
of them occurred on the scalp; this was not a bias resulting from a
longer duration before surgery. Trichoblastoma and not basal cell carcinoma
was the most frequent follicular tumor associated with NS and showed
a striking female predominance. Most trichoblastomas had previously
been misdiagnosed but could actually be easily recognized by typical
histologic features. Because most tumors occurred in adults older than
40 years, our study suggests that prophylactic surgery in young children
is of uncertain benefit. Clinical follow-up is probably sufficient,
and even those cases with clinical changes often proved to be benign
tumors or warts.

Basal cell carcinoma originating from a nevus sebaceus on the scalp
of a 7-year-old boy.

Basal cell carcinoma (BCC) occurs rarely in children and is most often
associated with an underlying condition that predisposes patients to
the development of malignancy. There have been numerous reports of BCC
developing after puberty in nevus sebaceus; however, such occurrences
have rarely been described in children.

We report a 7-year-old boy with BCC forming in a nevus sebaceus.

Malignant transformation in congenital sebaceous naevi in childhood.

Dunkin CS, Abouzeid M, Sarangapani K.

Department of Plastic and Reconstructive Surgery, Middlesbrough
General Hospital, UK.

They should be considered premalignant lesions as malignant degeneration,
most commonly basal cell carcinoma and squamous cell carcinoma, occurs
with a lifetime risk of between 5% and 22%. This incidence is equal
to that of actinic keratosis and exceeds that of oral leukoplakia. Such
change, however, is rare before puberty. Basal cell carcinoma may develop
in children with naevoid basal cell carcinoma syndrome, xeroderma pigmentosum
and rarely de novo but sebaceous naevus is the only solitary lesion
in childhood associated with the development of basal cell carcinoma.

We present two cases of malignant transformation in a congenital sebaceous
naevus occurring in childhood and review the literature and discuss
the evidence upon which to base management guidelines.

Ronald O. Perelman Department of Dermatology, New York University
Medical Center, New York.

Pediatr Dermatol 1993 Jun;10(2):189-91 Abstract quote

A 10-year-old boy from Guiana was born with a linear nevus sebaceus
covering his entire nose from the glabella area to the tip. Cosmetic
appearance, which was the major concern of the patient and his family,
was greatly improved by the use of the carbon dioxide (CO2) laser.

The CO2 laser has not been reported previously as a treatment modality
for nevus sebaceus.